LONDON — Fashion week, like all the seasonal holidays, brings people together. Otherwise, it’s hard to explain how you might find yourself cheek by jowl with male models and male models emeriti and the Formula One champion Lewis Hamilton, bouncing from one corner of London to another, navigating gridlock traffic between a temporary show encampment on the Thames and the Phillips auction house on Berkeley Square.

At teatime, you’re basking in the red light of Alexander McQueen’s seafaring show, where suits were embroidered with naval tattoos and lads’ hair was plastered to their heads as if they’d just been pulled from the brine, and before sunset, thumping at a giant London gay club for KTZ, the Bali-based streetwear line.

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At J. W. Anderson, the new accessory was a metal frame hung with key chains and trinkets.CreditNowfashion

Somewhere in the middle, you and the besuited editor of British GQ — Dylan Jones, also chairman of London Collections: Men — find time to visit Tom Ford in his thickly curtained digs on Sloane Street for a presentation that was like an impromptu drinks gathering, the designer himself appearing in his aviators at the end to offer small talk and handshakes to the nearest and dearest.

But by then, like clockwork, it’s on to the next location. London Collections: Men, newly enlarged to four days and scheduled from hour to hour, waits for no man.

Does a packed schedule equate to a slate of must-see shows? Not really. As London Collections: Men has grown, so has the amount of fat that could be judiciously trimmed from its menu. Scale is not a guarantee of success.

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Models peered through slits in Craig Green's fabric-and-wood sculptures.CreditTom Jamieson for The New York Times

Still, there have been moments, the head-scratching or pearl-clutching kind that still seem to animate London’s runways more than their counterparts in Milan or Paris, the kind of moments that make you wonder where men’s wear will go next.

Is the accessory-to-carry going to be a twisted bit of metal tubing dangling trinkets and key chains, like Jonathan Anderson of J.W. Anderson sent out on Sunday morning? Or is it the massive wood-and-cloth sculptures by Craig Green — not so much carried by their models as attached to them, forcing them to peer through tiny slits to see their way forward?

It will take time to digest suggestions like these. Critics are puzzling out think pieces as you read. (Metabolize quickly; Pitti Uomo in Florence, Italy, the next stop in the fashion circuit, begins this week.)

Still, for cutting through the clutter and the noise, few things work like shock. Which is why the most indelible image of the weekend was a parade of bare butts.

They came down the runway at 7 p.m. Saturday, care of the knitwear label Sibling. Its designers, Sid Bryan, Joe Bates and Cozette McCreery, had been thinking about jocks and football players (the American rather than the English type). They cited as their muse not the protein-shake-drinking gym men of today, but the hard-living N.F.L. hall of famer Len Dawson, who — at least according to their show notes — chugged beer at halftime and smoked.

There was enough to gawp at in the knit jockstraps, spangled jerseys and — for Sibling, arch provocateurs that its designers are — tailored suits. (The suits, a new addition for the brand, were made in collaboration with Edward Sexton, the well-known Savile Row tailor.) But then came the “bum freezer” trousers, scooped down in back like Alexander McQueen’s famous bumsters, to reveal a generous slice of (often unshaven) behind.

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At Sibling, football was the inspiration for spring 2016.CreditStuart C. Wilson/Getty Images

They were greeted with audible gasps. And then, inevitably, innumerable iPhone photos. Which is, at fashion week, as sure a sign of success as any.

Backstage, Mr. Bryan, Mr. Bates and Ms. McCreery were receiving guests and reporters. Longtime Sibling fans were in raptures, but what about newer fans? Had Mr. Sexton, a stalwart of Savile Row and a decades-long veteran of the industry, for instance, raised an eyebrow at any point during the collaboration process?

“He knows Sibling,” Mr. Bryan said. “He knows what we do. You just have to Google and you know what we do.”

And then Mr. Sexton, elegant in a gray suit and pink tie, appeared with his wife to offer congratulations.